如何Visual Studio的调试过程中显示System.Double？ [英] How does Visual Studio display a System.Double during debugging?

问题描述

尝试调试下面的简单程序，鼠标放在 X 中的每一个步骤（或添加监视为 X 或其他）

Try debugging the following simple program, and mouse over x in each step (or "Add Watch" for x or whatever).

using System;
using System.Globalization;

static class Program
{
  static double x;

  static void Main()
  {
    x = 2d;

    // now debugger shows "2.0", as if it has used
    // x.ToString("F1", CultureInfo.InvariantCulture)

    x = 8.0 / 7.0;

    // now debugger shows "1.1428571428571428", as if it had used
    // x.ToString("R", CultureInfo.InvariantCulture)
    // Note that 17 significant figures are shown, not the usual 15.

    x = -1e-200 / 1e200;

    // now debugger shows "0.0"; there is no indication that this is really negative zero
    //

    Console.WriteLine(1.0 / x); // this is negative infinity
  }
}

因此，显然有VS以自己的方式来显示一个 System.Double 。它调用哪个方法用于此目的？有没有一种方法可以让我得到了同样的字符串表示编程？

So, apparently VS has its own way to display a System.Double. Which method does it call for this purpose? Is there a way I can get the very same string representation programmatically?

（试过这一点与Visual Studio 2010专业版。）

(Tried this out with Visual Studio 2010 Professional.)

推荐答案

目前其核心都C＃和VB.Net EE的使用 _ecvt_s 函数用于格式化双成一个字符串。

At their core both the C# and VB.Net EE's use the _ecvt_s function for formatting a double into a string.

• 的 http://msdn.microsoft.com/en-us/library/ehz2dset（v = VS.80）的.aspx

• http://msdn.microsoft.com/en-us/library/ehz2dset(v=vs.80).aspx

无论做的结果字符串清理一点点，使显示更加C＃和VB一样，处理一些角落情况有点更好。无论是 _ecvt_s 函数或清理代码可以负责你看到的差异。很难说一目了然

Both do a little bit of cleanup on the resulting string to make the display more C# and VB like and handle some corner cases a bit nicer. Either the _ecvt_s function or the cleanup code could be responsible for the differences you see. Hard to tell at a glance

也许有人会问，为什么我们会经历这一切麻烦而不是说只叫的ToString 的值并显示。有几个原因，我们不这样做。

Some may ask why we would go through all of this trouble instead of saying just calling ToString on the value and displaying that. There are a couple of reasons we don't do this.

第一个是简单的功能评价，甚至的ToString ，是最昂贵的行动EE可以进行。常见的场景真正型材表明我们的时间超过98％用于做功能评价。任何时候，我们就可以避免一个函数计算，我们因为对性能的影响做。

The first is simply that function evaluation, even ToString, is the single most expensive action the EE can undertake. Profiles of common real scenarios show that over 98% of our time was spent doing function evaluation. Any time we can avoid a func eval we do because of the performance implications.

第二个原因很简单，功能评价并不总是可用。有一些情况下，如果函数计算是不可用的，但人们仍然期望看到像双击， INT 等......以他们离开将基本上杀调试经验。因此，我们必须在不的ToString 支持来解决这个问题。

The second reason is simply that function evaluation isn't always available. There are a number of cases where func eval is unavailable yet people still expect to see a display for primitive types like double, int, etc ... Taking them away would essentially kill the debugging experience. Hence we need to solve this problem without ToString support.

这篇关于如何Visual Studio的调试过程中显示System.Double？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！